Search Results
extending above the layer effectively form a coastal wall. The marine air acts as a single-layer incompressible fluid that responds hydraulically when the layer speed is sufficiently fast. If the Froude number is greater than 1, or supercritical, the speed of the layer is faster than the speed of long gravity waves in the layer and so that they cannot travel upstream. A supercritical marine layer moving around a corner, where the wall bends away from the flow, would accelerate and thin in the lee
extending above the layer effectively form a coastal wall. The marine air acts as a single-layer incompressible fluid that responds hydraulically when the layer speed is sufficiently fast. If the Froude number is greater than 1, or supercritical, the speed of the layer is faster than the speed of long gravity waves in the layer and so that they cannot travel upstream. A supercritical marine layer moving around a corner, where the wall bends away from the flow, would accelerate and thin in the lee
1. Introduction Over the last decade, numerical simulations of coastal ocean flows have begun to provide credible representations of three-dimensional, wind-forced, continental shelf circulation on horizontal scales of several to several hundred kilometers. On the central Oregon shelf, for example, primitive equation ocean models have been shown to yield useful comparisons with in situ and remote sensing observations, and have been used to obtain new insights into the structure and dynamics of
1. Introduction Over the last decade, numerical simulations of coastal ocean flows have begun to provide credible representations of three-dimensional, wind-forced, continental shelf circulation on horizontal scales of several to several hundred kilometers. On the central Oregon shelf, for example, primitive equation ocean models have been shown to yield useful comparisons with in situ and remote sensing observations, and have been used to obtain new insights into the structure and dynamics of
analysis will use coastal and satellite-estimated sea level data to determine whether the eddies off the southwest coast of Australia in the region of the Leeuwin Current dynamically affect the large-scale interannual flow and cause the interannual sea level amplitude to fall southward. In section 2 , the theory supporting this hypothesis will be discussed. We will then use coastal sea level station data and satellite altimetry data to document the interannual flow variability in section 3 . In
analysis will use coastal and satellite-estimated sea level data to determine whether the eddies off the southwest coast of Australia in the region of the Leeuwin Current dynamically affect the large-scale interannual flow and cause the interannual sea level amplitude to fall southward. In section 2 , the theory supporting this hypothesis will be discussed. We will then use coastal sea level station data and satellite altimetry data to document the interannual flow variability in section 3 . In
the radius of curvature) exceeds one ( Jiang 1995 ). In this situation, inertia would prevent the flow from following the isobath path, so the flow would cross isobaths. Insight from coastal hydraulics suggests that the straight shelf break and coastline curvature around capes can exert hydraulic control on the upwelling jet, leading to separation and increased upwelling downstream of the cape ( Dale and Barth 2001 ). Other mechanisms may produce additional upwelling or downwelling around capes
the radius of curvature) exceeds one ( Jiang 1995 ). In this situation, inertia would prevent the flow from following the isobath path, so the flow would cross isobaths. Insight from coastal hydraulics suggests that the straight shelf break and coastline curvature around capes can exert hydraulic control on the upwelling jet, leading to separation and increased upwelling downstream of the cape ( Dale and Barth 2001 ). Other mechanisms may produce additional upwelling or downwelling around capes
discussed in Part I . The alongshelf asymmetry of the Heceta Bank complex bathymetry, however, can cause significant differences. The tightly curved isobaths on the south side of the bank may cause pronounced flow separation from isobaths. Wind-driven flow in the vicinity of the Heceta Bank complex has been observed and previously modeled. The most recent study is the Coastal Ocean Advances in Shelf Transport (COAST) project funded by the National Science Foundation. Intensive field efforts observed
discussed in Part I . The alongshelf asymmetry of the Heceta Bank complex bathymetry, however, can cause significant differences. The tightly curved isobaths on the south side of the bank may cause pronounced flow separation from isobaths. Wind-driven flow in the vicinity of the Heceta Bank complex has been observed and previously modeled. The most recent study is the Coastal Ocean Advances in Shelf Transport (COAST) project funded by the National Science Foundation. Intensive field efforts observed
and extensive lists of references can be found in Pedlosky (1979) and Pierrehumbert and Swanson (1995) . Further descriptions of the extensions of interest in this study are given in section 2 . In the context of coastal baroclinic instability, the Eady-type models described above have been invoked to inform interpretation and parameterizations. For slope effects, a number of recent studies on unstable flow over topography have reported evidence of slope stabilization in a manner consistent
and extensive lists of references can be found in Pedlosky (1979) and Pierrehumbert and Swanson (1995) . Further descriptions of the extensions of interest in this study are given in section 2 . In the context of coastal baroclinic instability, the Eady-type models described above have been invoked to inform interpretation and parameterizations. For slope effects, a number of recent studies on unstable flow over topography have reported evidence of slope stabilization in a manner consistent
barrier jets typically occur when there is an upper-level trough over the Aleutian Islands and a ridge over western Canada, which favors low-level southerly flow impinging toward the Alaskan coastal terrain ( Colle et al. 2006 ). The mesoscale structure of barrier jets in southeast Alaska was investigated using research aircraft measurements collected during the Southeastern Alaskan Regional Jets (SARJET) experiment between 24 September and 21 October 2004 ( Fig. 1 ; Winstead et al. 2006 ). SARJET
barrier jets typically occur when there is an upper-level trough over the Aleutian Islands and a ridge over western Canada, which favors low-level southerly flow impinging toward the Alaskan coastal terrain ( Colle et al. 2006 ). The mesoscale structure of barrier jets in southeast Alaska was investigated using research aircraft measurements collected during the Southeastern Alaskan Regional Jets (SARJET) experiment between 24 September and 21 October 2004 ( Fig. 1 ; Winstead et al. 2006 ). SARJET
barrier jets typically occur when there is an upper-level trough over the Aleutian Islands and a ridge over western Canada, which favors low-level southerly flow impinging toward the Alaskan coastal terrain ( Colle et al. 2006 ). The mesoscale structure of barrier jets in southeast Alaska was investigated using research aircraft measurements collected during the Southeastern Alaskan Regional Jets (SARJET) experiment between 24 September and 21 October 2004 ( Fig. 1 ; Winstead et al. 2006 ). SARJET
barrier jets typically occur when there is an upper-level trough over the Aleutian Islands and a ridge over western Canada, which favors low-level southerly flow impinging toward the Alaskan coastal terrain ( Colle et al. 2006 ). The mesoscale structure of barrier jets in southeast Alaska was investigated using research aircraft measurements collected during the Southeastern Alaskan Regional Jets (SARJET) experiment between 24 September and 21 October 2004 ( Fig. 1 ; Winstead et al. 2006 ). SARJET
TRs—based on whether the offshore distance of the formative location was less than or greater than 40 km. Their detailed composite analyses of low-level radar-derived airflow patterns within and adjacent to the TRs indicated that the formation of the nearshore TRs was closely related to the low-level convergence that was produced as coastal offshore flow encountered synoptic onshore flow. In distinct contrast, the formation of the offshore TRs appeared to be more related to the deceleration of
TRs—based on whether the offshore distance of the formative location was less than or greater than 40 km. Their detailed composite analyses of low-level radar-derived airflow patterns within and adjacent to the TRs indicated that the formation of the nearshore TRs was closely related to the low-level convergence that was produced as coastal offshore flow encountered synoptic onshore flow. In distinct contrast, the formation of the offshore TRs appeared to be more related to the deceleration of
orographic lifting of moist air on the windward slopes of the mountains and intensified further by convergence and vertical motions resulting from subsynoptic interactions with terrain trapped airflows (TTAs) flowing parallel to the coastal ranges. Terrain blocking is one mechanism for forming a TTA, with high static stability conducive to onshore flow turning parallel to rather than over higher terrain. The local blocking decelerates the flow, with pressure rises along the windward slopes. To balance
orographic lifting of moist air on the windward slopes of the mountains and intensified further by convergence and vertical motions resulting from subsynoptic interactions with terrain trapped airflows (TTAs) flowing parallel to the coastal ranges. Terrain blocking is one mechanism for forming a TTA, with high static stability conducive to onshore flow turning parallel to rather than over higher terrain. The local blocking decelerates the flow, with pressure rises along the windward slopes. To balance
